The present invention relates generally to an apparatus and method of terminating and securing wires to a stator for an internal combustion engine, and more particularly to a multiple pole stator having a plurality of openings extending through the core of the stator for terminating and securing lead wires therein. The design of the present invention provides a more reliable and more cost effective method of terminating and securing lead wires to a stator.
A stator for use in ignition and charging systems of an internal combustion engine typically comprises a central core having a plurality of poles extending outwardly from the periphery of the core. The periphery of the core and the poles are electrically insulated from the central core by an insulating material. Wire is wound on the poles to produce wire coils around each of the poles. The wire coils are electrically connected to lead wires from ignition or charging system circuitry and/or components by soldering, brazing, crimping, splicing, or other known methods of connecting wires together. In the prior art, this wire connection and termination is made between stator poles. The termination is encapsulated with an epoxy or potting compound to hold the wires in place. Examples of prior art stator assemblies are shown in FIGS. 1–4.
Referring to the drawings, FIGS. 1 and 2 illustrate one embodiment of a prior art stator assembly 10 illustrating termination and securing of lead wires 12 between stator poles 14. As shown, the termination area 16 between the wire coils 18 on the stator poles 14 is completely encapsulated by an epoxy or potting compound 20. This prevents airflow through and around the poles 14, increasing the operating temperature of the stator and possibly causing failures. Also, the lead wires 12 are shown extending above the top of the stator 10, requiring a significant clearance area above the stator in its final assembly.
FIGS. 3 and 4 illustrate another embodiment of a prior art stator assembly 30 illustrating termination and securing of lead wires 32 between stator poles 34. This embodiment also shows the termination area 36 between the wire coils 38 of the stator poles 34 being completely encapsulated by an epoxy or potting compound 40, thus preventing airflow through and around the poles 34. The lead wires 32 are also shown extending above the top of the stator 30, requiring a significant clearance area above the stator in its final assembly.
Additional problems with prior art terminations include fitting the termination between the poles of the stator. Often, the wire coils around the poles are so close together that the termination will not fit. The termination is typically taped or covered with shrink sleeving, increasing its size. There are also problems with shorts occurring between the lead wires and the insulated copper wires of the wire coils wound around the stator poles. Wires soldered or crimped together can have sharp burrs that pierce the tape or shrink sleeve covering the termination causing shorts between the termination and wire coils because of the termination's proximity to the wire coils.
U.S. Pat. No. 6,137,198 discloses a stator for a magneto generator comprising a stator core having a holding fixture mounted to the top of the stator core for connecting lead wires to the wire coils wound around the stator poles. This invention does not solve all of the problems discussed above, because the wires extend too far above the stator core. The stator in the '198 patent is mounted on a crankcase cover where there is enough clearance above the stator for wires to extend. There are other applications, such as in the present invention, where the stator is mounted under a rotor on the crankcase. With the rotor mounted above the stator, there is very little room between the stator and the rotor for wires to extend.